Voyager58,
I have walked in winter several times; February /March 2006,2007, January /March 2008, 2009, and 2010
Be sure to read what other pilgrims and I have written about
winter walking in this earlier Forum thread.
Sillydoll who is a Forum member has compiled encyclopedic information on Winter Walking at >>
http://amawalker.blogspot.com/ Another good account of winter walking by a Forum member is the earlier 2013 blog
http://agoodwalkunspoiled.blogspot.com/ .
The best advice is to BE PREPARED for extreme and varied weather. Nights can be bitter cold with freezing rain or snow. Learn to read the sky for possible storms.
Regarding the state of the path and weather forecasts be sure to ask the locals and watch TV reports. Not all albergues will be open but the hospitaleros usually know who is on the next stage. You will find the welcome at those albergues which are open to be most sincere; generally they will either be heated or have blankets, but not all.
In bad weather many steep descents on the camino would be treacherous and following smaller parallel roads might be necessary. This past winter/early spring the Napoleon route from SJPdP to Roncevalles was filled with several meters of snow and in effect closed to pilgrims thus necessitating the use of the Valcarlos alternate. You can read about this situation in the Forum topic. >>
el-camino-frances/topic16961.html Other difficult stretches after future storms might be from Najera to Santo Domingo de la Calzada or across the Montes de Oca from Villafranca as well as Monte Irago and, of course, O Cebriero.
Twice walking during winter caminos I have sat out true blizzards; in Villafranca Montes de Oca, February 25, 26, 2006 and Foncebadón, March 5,6, 2009. Even late last November the climb up to O Cebriero was packed with snow. You can see the snow and read my blog accounts of these three memorable stormstorms at >>
http://mermore.blogspot.fr/2011/04/aavmo.html. Luckily open albergues offered welcoming shelter, heat and companionship.
Have a safe and warm Buen Camino,
Margaret Meredith